The mobile IPv6 (refer to IETF RFC3775, Mobility Support in IPv6) is a protocol that enables communications even during moving from a network to another with use of the same IP address. The mobile IPv6 protocol uses networks, each of which includes a mobile node (MN) that enables communications during moving among plural networks, a home agent (HA) that manages position information of the MN, and a correspondent node (CN) that communicates with the MN. The MN registers the correspondence (binding information) between each IP address (HoA: Home Address) and each IP address (CoA: Care of Address) periodically in the HA. The (HoA: Home Address) is never changed even during moving among plural networks and the (CoA: Care of Address) is assigned dynamically at each destination network. The HA catches IP packets addressed to the HoA from the CN and encapsulates the IP packets with use of the IPv6 header in which its address is set as the source address and the CoA of the MN is set as the destination address. The HA then transfers the encapsulated IP packets to the MN. The MN decapsulates the packets received from the HA and processes the packet data. On the other hand, as for the packets addressed to the CN from the MN, the MN encapsulates those packets with use of the IPv6 header in which the MN address is set as the source address and the HA is set as the destination address, then transfers the encapsulated packets to the HA. The HA decapsulates the received packets and transfers the packet data to the CN. This is why the communications are enabled with use of the same IP address even during moving among plural networks.
There is a third generation (3G) mobile communication system standardized with the 3GPP2 (3rd Generation Partnership Project 2). The system is regarded as an example of the communication system that uses the mobile IPv6 protocol.
The 3G mobile communication system consists of a radio access network (RAN) and a core network. The RAN has functions used to terminate and control radio transmission functions. The core network has functions used to control movements and services. The core network includes an access gateway (PDSN: Packet Data Serving Node) and an HA. The PDSN is connected to the MN with use of the PPP, thereby supplying IP connecting functions. The core network supplies IP communication functions on the basis of the mobile IP.
On the other hand, the 3GPP2 standardizes a service control network connected to the core network as an MMD (Multimedia Domain) (3GPP2 X. P0013-002-B v0.3, All-IP Core Network Multimedia Domain; IP Multimedia Subsystem Stage2 and 3GPP2 X. P0013-004-B v0.06, All-IP Core Network Multimedia Domain; IP Multimedia Call Control Protocol Based on SIP and SDP Stage3). The MMD uses the SIP (Session Initiation Protocol)/(SDP (Session Description Protocol) as a control protocol employable for telephones and IM (Instant Messaging) services.
Furthermore, the 3GPP2 specifies a method for the cooperation between the service based bearer control (SBBC) used to control the MMD services and the RAN QoS so as to make QoS control appropriately to each object service (3GPP2 X. P0013-012-B v0.21, All-IP Core Network Multimedia Domain; Service Based Bearer Control—Stage2; 3GPP2 X. P0013-013-0 v0.11, All-IP Core Network Multimedia Domain; Service Based Bearer Control Tx Interface Stage3; 3GPP2 X. P0013-014-0 v0.11, All-IP Core Network Multimedia Domain; Service Based Bearer Control Ty Interface Stage3). The SBBC includes a QoS policy server (PCRF: Policy and Charging Rules Server) disposed between the MMD service control server (AS: Application Server) and the access network. The AS notifies the PCRF of the service information (communication address, port No., codec, band width, etc.) obtained upon processing such a service control protocol as the SIP/SDP or the like. The PCRF determines the object QoS according to the service information notified from the AS and notifies the RAN of the determined QoS through the PDSN.
The RAN controls the QoS appropriately to each application program according to the QoS parameters determined by the PCRF (3GPP2 X. P0011-004-D v1.0, cdma2000 Wireless IP Network Standard: Quality of Service and Header Reduction). For example, the RAN uses a communication channel secured for a fixed bandwidth and with less delay and jittering to send voice traffics that are often sent in real time. On the other hand, the RAN uses a best effort communication channel to send IM and Web services.
In the RAN, each IP flow that belongs to each application program is specified with filter information (source/destination IP address, port No., etc.) referred to as a TFT (Traffic Flow Template). Each of the MN and the PDSN manages the correspondence between TFT and communication channel to transfer IP flows through a proper communication channel. Each terminal transfers packets in the reverse direction matching with the TFT through the communication channel corresponding to the TFT. The PDSN carries out the same processings for the packets transferred in the forward direction.